The present invention relates to an optical system for recording information in an optical recording medium with a converged light beam and for reproducing it therefrom.
In some recent optical recording media, information can be recorded with a converged laser beam, reproduced therefrom, and erased.
User information to be recorded in the information recording medium includes temporal data and permanent data. Temporal data is recorded and is erased when such data is not necessary, and new data is recorded in the information recording medium. Alternatively, rough data is temporarily recorded, and is partially updated later. Permanent data includes "manufacture number and date of information recording medium", "data index", and "classification items of contents to be recorded", which must not be erased.
Conventional information recording media are classified into media only with an information erasable region or media only with a nonerasable region. However, no conventional information recording medium has both erasable and nonerasable regions. Therefore, when a user wishes to record temporal and permanent data in information recording media, he must use two types of information recording media, resulting in inconvenience.